During extended periods of exposure to a gravity free environment such as experienced by astronauts, the body's fluids redistribute in response to the weightless environment. This fluid change triggers responses in the autonomic nervous and cardiovascular systems which, when coupled with low humidity conditions in space vehicles, results in progressive fluid volume loss and symptoms associated with dehydration. This is called “orthostatic intolerance.” Attempts have been made to resolve these problems upon return to Earth by applying various types of compression garments to the astronauts upon return to Earth. However, prior efforts have been limited by variation in the amount of fluid volume loss from astronaut to astronaut, so that in some cases the compression garments were so loose that they did not function adequately.
To counter the effects of orthostatic intolerance upon return to earth's gravitational force, it has been determined that it is desirable to use a “gradient compression garment,” and to maintain a desired compression profile even with dimensional changes in the body. The primary areas of concern are the upper thigh and abdomen.
A second need is to provide a means of gradually returning the astronauts back to normal gravitational exposure. To accomplish this, it is proposed to provide a means in which the compression level can be incrementally reduced.
There are multiple advantages that the system described below provides over current garments and garment system. First, the system may serve to adjust the compressive force (fabric tension) over areas of the body most susceptible to volume loss during extended exposure to a non-gravity environment. Second, the system may provide precise adjustments of the garment to ensure a continuous applied pressure gradient, being highest at the ankle and decreasing proximally. Third, the system may permit gradually reintroducing the astronaut to normal gravitational forces upon return to earth after extended stays in weightlessness. Fourth, the system may apply compression to the wearer promptly after re-entry into a gravity environment without the need for an air supply or electrical power for pumps or other pressure-inducing means.